In Leiden Manifesto (LM) (Hicks et al 2015) bibliometric evaluation is explained as a combination of quantitative and qualitative methods, allowing the use of different metrics, disciplinary knowledge and research performance strategies. Both bibliometricians and consumers of bibliometrics are encouraged to communicate and use the LM principles to acknowledge what they know and do not know, what is measured and what is not measured, thus legitimizing the use of metrics applied in an evaluation. However, we have previously observed that it is unclear how the LM principles should be interpreted in a concrete evaluation and that evaluations may differ in their interpretations of the LM principles. Our concern is that interpretations randomly differ from case to case. The present study investigates how the LM principles have been interpreted in concrete evaluations. Based on the investigation we suggest possible future developments of the LM.